This invention relates to a taper-boring machine for taper-boring an inner surface of a pipe fitting.
Throughout this specification the term xe2x80x9cpipe fittingxe2x80x9d refers to fittings and connectors such as elbows of varying angles, T-pieces, reducers flanges and the like.
In instances where a thicker walled fitting is welded to a thinner walled pipe, the inner wall of the fitting adjacent to the weld is taper-bored before the fitting is welded to the pipe. If this were not done a step would exist at the interface between the pipe and the fitting due to the different wall thicknesses of the pipe and the fitting. This step would increase the turbulence of a fluid flowing through the pipe and the fitting, thereby increasing friction losses.
Conventionally, a fitting is taper-bored using a circular boring machine which is inserted into the end of the fitting. A problem which exists with taper-boring fittings in this way is that the boring machine must be concentrically placed otherwise an asymmetric bevelled edge is created on the fitting. Furthermore, the boring machine can only be used in fittings which have been circular cross-section and it cannot be used in fittings which have been distorted through use, manufacturing defects or damage in transit.
According to the invention there is provided an apparatus for taper-boring a bevelled surface into an inner wall of a pipe fitting, the apparatus comprising:
support means for supporting the fitting on the apparatus;
drive means for rotating the fitting with respect to the apparatus;
a rotatable milling head locatable at least partially within the fitting on the fitting being supported by the support means,
the arrangement of the support means and the milling head being such that the fitting is rotatable with respect to the milling head.
Preferably, the milling head is moveable, more particularly pivotable, with respect to a fitting supported by the support means.
The support means may comprise at least three rotatable rollers displaced from one another in a triangular arrangement and defining a space between the rollers in which a fitting is supportable.
Typically, the drive means is provided on one of the three rollers.
Preferably, at least one of the rollers is moveable with respect to the other rollers so as to allow different sized fittings to be accommodated in the space between the rollers.
An embodiment of the invention is described in detail in the following passages of the specification which refer to the accompanying drawings. The drawings, however, are merely illustrative of how the invention might be put into effect, so that the specific form and arrangement of the features shown is not to be understood as limiting on the invention.